trace element
trace mineral
microelement

There was no use trying to explain that what he needed were trace elements.

There is also a host of trace elements and almost always some organic matter.

It was originally created from a number of different materials including various trace elements.

His main area of research has been the role of trace elements in the human body.

The determination of trace elements can sometimes help with mint problems.

Iron is a necessary trace element found in nearly all living organisms.

We all have to have it as a trace element.

Numerous trace elements have also been found in batches of 714-X.

But never with the key trace elements which comprise the compound needed.

Something about trace elements determining the colors of a plant's flowers.